SV-217277r991589: The SUSE operating system SSH daemon must perform strict mode checking of home directory configuration files. | SUSE Linux Enterprise Server 12 STIG SCAP Benchmark

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Assessment Title

Rule Text

The SUSE operating system SSH daemon must perform strict mode checking of home directory configuration files.

Description

Discussion Text

If other users have access to modify user-specific SSH configuration files, they may be able to log on to the system as another user.

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-000366SV-92163V-77467

References

DPMS Target SUSE Linux Enterprise Server 12 DISA DPMS Target SUSE Linux Enterprise Server 12 4033

Checks

DISA STIG (Manual Reference)

Verify the SUSE operating system SSH daemon performs strict mode checking of home directory configuration files.

Check that the SSH daemon performs strict mode checking of home directory configuration files with the following command:

# sudo grep -i strictmodes /etc/ssh/sshd_config

StrictModes yes

If "StrictModes" is set to "no", is missing, or the returned line is commented out, this is a finding.

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

#!/bin/bash
# Reconstructed from oval:mil.disa.stig.sles12:def:234
# The SUSE operating system SSH daemon must perform strict mode checking of home directory configuration files.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# The openssh package is installed
# rpminfo_object (rpminfo_test)
test_1() {
  rpm -q --quiet 'openssh' &>/dev/null
}
# The ssh daemon is running
# process58_object (process58_test)
test_2() {
  ps -eo args | grep -P '^/usr/sbin/sshd\b' &>/dev/null
}
# /etc/ssh/sshd_config:StrictModes == yes
# textfilecontent54_object (textfilecontent54_test)
test_3() {
  (sed -En 's/^\s*(?i)StrictModes(?-i)[ \t]+([\w\"]+)[\s]*(?:|(?:#.*))?$/\1/p' '/etc/ssh/sshd_config') | grep -Pq '^(yes|"yes")$'
}

if ( test_1 && test_2 && test_3 ); then
  echo "PASS"
else
  echo "FAIL"
fi

Assessment Script Powered by AISandbox-executed

A standalone Shell script to assess this control automatically. Review before running it in your environment.

Syntax-checked and actually executed in an isolated sandbox (not the real system this checks) — confirmed to run without errors.

#!/bin/sh
# DISA STIG / SCAP compliance check for SUSE SSH strict mode checking
if [ ! -x "$(command -v rpm)" ]; then echo "FAIL"; exit 1; fi
if rpm -qa --querytags Name | grep -q "^openssh$"; then
    if ps -p 1 -o comm= | grep -q "^sshd$"; then
        if grep -qE "^\\s*(?i)StrictModes(?-i)[ \\t]+yes[\\s]*(?:|(?:#.*))?$" /etc/ssh/sshd_config; then
            echo "PASS"; exit 0
        else
            echo "FAIL"; exit 1
        fi
    else
        echo "FAIL"; exit 1
    fi
else
    echo "FAIL"; exit 1
fi

Remediation

Configure the SUSE operating system SSH daemon performs strict mode checking of home directory configuration files.

Uncomment the "StrictModes" keyword in "/etc/ssh/sshd_config" and set the value to "yes":

StrictModes yes